The present invention is directed to a method of and a fastening element for securing reinforcement to a surface of concrete structural components, such as ceilings, beams and the like, where metal reinforcing members are bonded to a surface of the structural components in the tension zone of the component.
As is well known, concrete structural components are provided with reinforcing members while they are being constructed. Such structural components can be ceilings or covers, beams, bridges and the like.
If structural components must be reinforced due to changed external conditions, for instance if an increase in carrying capacity is desired, the use of additional reinforcing members is necessary. Since additional reinforcement can not be accommodated within the components without destroying them, it has been known to attach additional reinforcement by bonding to the surface of the structural components. The tension zone of the structural components is available for reinforcing members capable of being stressed in tension. As a rule, such reinforcement is formed of sectional steel, particularly sheet steel.
When structural components with such additional reinforcing members are subjected to a load, a relative offset in length takes place between the components and the reinforcing members due to the bending deflection of the structural components. Such offset may be of such a magnitude at the ends of the reinforcing members that they separate from the component. In such a situation, the weak point is not the bonding, but the component formed of concrete. In such a situation, while concrete can be highly loaded in compression, it is prone to failure if loaded in shear or tension. This condition results in a destruction of the concrete at the ends of the bonded reinforcement with a part of the component being torn off from the ends of the reinforcing members due to the relative offset.